
EN(STI)(diag)-377
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
13 CHECK MASS AIR FLOW AND INTAKE AIR
TEMPERATURE SENSOR.
1) Start the engine and warm up engine until
coolant temperature is higher than 75°C
(167°F).
2) Place the shift lever in neutral position.
3) Turn the A/C switch to OFF.
4) Turn all the accessory switches to OFF.
5) Open the front hood.
6) Measure the ambient temperature.
7) Read the value of «Intake Air Temp.» using
the Subaru Select Monitor or a general scan
tool.
NOTE:
• Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(STI)(diag)-36, Subaru Select Monitor.>
• General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Subtract ambient temperature
from «Intake Air Temp.». Is the
obtained value –10 — 50°C (–18
— 90°F)?
Go to step 14. Check the mass air
flow and intake air
temperature sen-
sor. <Ref. to
FU(STI)-40, Mass
Air Flow and Intake
Air Temperature
Sensor.>
14 CHECK REAR OXYGEN SENSOR DATA.
1) Warm up the engine until engine coolant
temperature is higher than 75°C (167°F), and
keep the engine speed at 3,000 rpm. (2 minutes
maximum)
2) Read the value of «Rear O2 Sensor» using
the Subaru Select Monitor or a general scan
tool.
NOTE:
• Depress the clutch pedal.
• Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(STI)(diag)-36, Subaru Select Monitor.>
• General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Rear O2 Sen-
sor» 0.490 V or more?
Go to step 15. Go to step 16.
15 CHECK REAR OXYGEN SENSOR DATA.
1) Warm up the engine until engine coolant
temperature is higher than 75°C (167°F), and
rapidly reduce the engine speed from 3,000
rpm.
2) Read the value of «Rear O2 Sensor» using
the Subaru Select Monitor or a general scan
tool.
NOTE:
• Depress the clutch pedal.
• Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(STI)(diag)-36, Subaru Select Monitor.>
• General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
Is the value of «Rear O2 Sen-
sor» 0.250 V or less?
Go to step 17. Go to step 16.
16 CHECK REAR OXYGEN SENSOR CONNEC-
TOR AND COUPLING CONNECTOR.
Has water entered the connec-
tor?
Completely
remove any water
inside.
Go to step 18.
Step Check Yes No
15WRX_STI_US_EN.book 377 ページ 2015年2月13日 金曜日 午前11時20分